Bacterial iron uptake transport systems (BITS)

Bacterial iron uptake transport systems are specialized protein complexes used by bacteria to scavenge iron from the host environment, where the metal is typically sequestered by proteins like transferrin and ferritin (Kramer et al., 2020, Nature Reviews Microbiology). These systems, which include TonB-dependent transporters (TBDTs) in Gram-negative bacteria and various ABC transporters, are essential for bacterial growth, DNA replication, and virulence (Noinaj et al., 2010, Annual Review of Microbiology). Because iron is a limiting factor for infection, these transport pathways represent a critical vulnerability in bacterial pathogenesis. Modern therapeutic strategies exploit these systems using a Trojan horse approach, where antimicrobial agents are conjugated to siderophores—small, high-affinity iron-chelating compounds. The drug Cefiderocol is a primary clinical example of this strategy, utilizing the bacteria's own iron transport machinery to cross the outer membrane and reach its target (Shakoor et al., 2021, Antibiotics). By targeting these systems, clinicians can potentially overcome common resistance mechanisms such as decreased porin expression or increased efflux. However, the development of resistance through mutations in transport genes and the complexity of redundant iron acquisition pathways remain significant hurdles in drug development (NIH/PubChem, 2024).

Other names

Siderophore transport systemsTonB-dependent transport systemsHeme acquisition systemsFerric iron transport systemsBacterial iron acquisition machinery

Siderophore-mediated active transport (Trojan horse mechanism) where drugs are conjugated to siderophores to bypass the outer membrane barrier; competitive inhibition of iron binding; and utilization of iron-mimetic compounds to disrupt bacterial metabolism.